[单项选择] You are implementing an ASP.NET Web site that uses a custom server control named Task. Task is defined as shown in the following list.    Class name： Task   Namespace： DevControls   Assembly： TestServerControl.dll   Base class： System.Web.UI.WebControls.WebControl    You copy TestServerControl.dll to the Web site‟s Bin folder.  You need to allow the Task control to be declaratively used on site pages that do not contain an explicit @ Register directive.  Which configuration should you add to the web.config file？（）
A. <appSettings> <add key="Dev:Task" value="DevControls, DevControls.Task"/> </appSettings>  
B. <compilation targetFramework="4.0" explicit="false"> <assemblies> <add assembly="TestServerControl" />      </assemblies> </compilation>
C. <pages> <controls> <add assembly="TestServerControl" namespace="DevControls" tagPrefix="Dev"/>      </controls> </pages>
D. <pages> <tagMapping> <add tagType="System.Web.UI.WebControls.WebControl"  mappedTagType="DevControls </tagMapping> </pages>